The amount left of the Mackinaw peach that Kramer's (Michael Richards) eating keeps varying between shots.
When George says, "She thinks I'm ugly!" and sits on the couch, he faces forward. When Jerry goes to sit next to him, George is suddenly looking up and to the side.
When fumigating a residence all openings are sealed up with plastic. There should be plastic around the door. Also, the gas is visible, but in the apartment no gas is seen.
Elaine is wearing a watch when she talks to the lady from Viking press about the manuscript. When she later approaches Jerry about retrieving the manuscript from his fumigated apartment, the watch is gone.
The second time that Elaine (Julia Louis-Dreyfus) goes to Jerry's (Jerry Seinfeld) apartment, a bright light can be seen through the door crack. When she goes in, though, there are no lights on.